1. Field of the Invention
The present invention relates to a paper feeding device, and more particularly to a paper feeding device having a paper blocking unit applied in an office business machine.
2. The Related Art
Recent business machines, such as a scanner, a printer, a copier, etc., are broadly required in the office operation. The business machine has a function of image disposing. Take a conventional scanner as an example, an image disposing system of the scanner includes a glass plate, an optical system arranged under the glass plate for reading the image of the paper placed on the glass plate. As a result of the application of the ADF (automatic document feeder), a stack of papers are placed in a paper tray of the ADF, then the papers are fed into the scanner one by one and placed on the glass plate by a paper feeding device of the ADF, at last, the optical system reads the image of the paper.
In the conventional scanner, the paper feeding device further comprises a paper blocking unit, which is used to make sure that the paper is placed in a proper position before being picked by the paper feeding device, thereby, the paper is picked by a pickup roller of the paper feeding device.
Please refer to FIGS. 1-2, a conventional paper feeding device 1′ having a paper blocking unit includes a separating roller 10′, a pickup roller 20′, a blocking unit 30′ and a blocking arm 40′. The separating roller 10′ and the pickup roller 20′ are parallel to each other and located in a roller frame 50′, the blocking unit 30′ sleeves on the shaft of the pickup roller 20′. The blocking arm 40′ is located on the roller frame 50′. Before the paper being picked, a blocking projection 41′ of the blocking arm 40′ leans against a stopping projection 31′ of the blocking unit 30′, the papers 2′ are stopped outside, the pickup roller 20′ keeps a certain distance from the papers 2′. Then referring to FIG. 2, when the paper 2′ is to be picked, the roller frame 50′ drives the pickup roller 20′ to move downwards, the blocking arm 40′ rotates and the blocking projection 41′ impels the stopping projection 31′ of the blocking unit 30′ to move upwards, as a result, the blocking arm 40′ loses the cooperation with the blocking unit 30′, then the papers 2′ are not stopped by the blocking arm 40′. At the same time, the pickup roller 20′ contacts with the paper 2′ and the paper 2′ are fed into the scanner one by one via the paper feeding device 1′.
As described above, the blocking projection 41′ impels the stopping projection 31′ of the blocking unit 30′ to move upwards, thereby, the blocking arm 40′ loses the cooperation with the blocking unit 30′, then the paper 2′ are not stopped by the blocking arm 40′ and fed into the scanner one by one. However, the cooperation between the blocking arm 40′ and the blocking unit 30′ is liable to be lost, then the blocking projection 41′ isn't able to impel the stopping projection 31′ to move. Consequently, the paper 2′ isn't able to be fed into the paper feeding device 1′, so the paper feeding device 1′ can not work smoothly.